Users of mobile communication devices and content providers for the mobile communication devices expect the devices to be provided with a suite of software that makes the operation of the mobile communication device secure and the handling of the content fair to the content providers. Mobile communication device providers also want to protect their software from being copied and modified by other mobile communication device providers or users. Mobile communication device providers or manufacturers therefore include security mechanisms in their devices and in their software that put restrictions on the software that can be used in the devices and stop the software from being modified to, for example, circumvent subscriber identity module (SIM) lock and digital rights management (DRM) protection mechanisms.
One way of protecting software is for mobile communication device providers to encrypt their software images and to program the integrated circuits (ICs) of their mobile devices with a root key related to a key certificate comprising a key for decrypting the software image. Another way involves providing the software image without encryption but adding a digital signature to it. The signature is then compared to a key in the key certificate associated with the root key of the IC. Encrypting or signing the software ensures that only a device programmed with the right key can run the software. If the manufacture of ICs is outsourced, the manufacturer of the ICs can program the ICs with the key of the mobile communication device provider to which the ICs are sold.
Mobile communication device providers may also instruct the IC manufacturer to program the IC with code needed for booting up the system and critical system libraries.
The invention was made in this context.